1. Field of the Invention
This invention relates to a disc cartridge containing a disc-shaped recording medium such as optical disc.
This application claims priority of Japanese Patent Application No. 2004-003444, filed on Jan. 8, 2004 and Japanese Patent Application No. 2004-140471, filed on May 10, 2004, the entireties of which are incorporated by reference herein.
2. Description of Related Art
Disc cartridges rotatably containing a disc-shaped recording medium such as optical disc so as to be loaded in a recording and/or reproduction apparatus with the disc-shaped recording medium contained therein have been and are being used popularly. Disc cartridges of the type under consideration are adapted to protect the disc-shaped recording mediums contained therein and to be loaded in and unloaded from a recording and/or reproduction apparatus with ease.
To make disc cartridges adapted to be loaded in and unloaded from a recording and/or reproduction apparatus with a disc-shaped recording medium contained therein, the cartridge main body is provided with a drive aperture for receiving the turn table of a rotary disc drive mechanism for driving the disc-shaped recording medium to rotate and a recording and/or reproduction aperture for exposing part of the signal recording region of the disc-shaped recording medium extending between the inner periphery and the outer periphery of the disc-shaped recording medium to the outside.
The drive aperture is circular and formed substantially at the center of one of the opposite surfaces of the cartridge main body so as to expose a central part of the disc-shaped recording medium contained in the cartridge main body where a center hole is bored. On the other hand, the recording and/or reproduction aperture is formed on one or both of the opposite surfaces of the cartridge main body. The recording and/or reproduction aperture formed on one of the opposite surfaces of the cartridge main body has a rectangular contour and extend from a position close to the drive aperture to a lateral side of the cartridge main body.
As the disc cartridge is loaded in a recording and/or reproduction apparatus, the disc-shaped recording medium contained in the disc cartridge receives the turn table of the apparatus through the drive aperture. As the disc-shaped recording medium is driven by the turn table to rotate, the signal recording region thereof is scanned by the recording/reproduction head section of the recording and/or reproduction apparatus, which may typically an optical pickup to which the recording and/or reproduction aperture is exposed, and information is recorded and/or reproduced.
Meanwhile, if the recording and/or reproduction aperture of the cartridge main body is left uncovered, dust can enter the cartridge main body when the disc cartridge is not loaded in a recording and/or reproduction apparatus and simply stored in a storage to contaminate and damage the disc-shaped recording medium contained in the cartridge main body.
Therefore, disc cartridges containing a disc-shaped recording medium are provided with a shutter member for closing at least the recording and/or reproduction aperture. The shutter member is fitted to the disc cartridge so as to be movable between a position where it closes the recording and/or reproduction aperture and a position where it exposes the recording and/or reproduction aperture.
Some disc cartridges containing a disc-shaped recording medium are provided with a drive aperture having a recording and/or reproduction aperture only on one of the opposite surfaces thereof. Since such disc cartridges do not have any opening on the other surface, the entire surface can be used to carry a label or a design can be directly printed thereon.
Thus, disc cartridges having openings only on one of the surfaces are provided with a shutter member for opening and closing the recording and/or reproduction aperture whose shutter section extends only on the surface of the cartridge main body where the openings are arranged. The shutter section of the shutter/guide member for opening and closing the recording and/or reproduction aperture extends only on that surface of the cartridge main body and the shutter/guide member is a cantilever type member that is fitted to a lateral side of the cartridge main body by way of a support section arranged at the base of the shutter section.
Since the shutter member having the above-described profile is supported by the cartridge main body only at the base of the shutter section, its front end may lift up from the surface of the cartridge main body. Additionally, when the disc cartridge is put into a recording and/or reproduction apparatus, the shutter member is subjected to the force that is applied to the shutter opening/closing member of the recording and/or reproduction apparatus at the base thereof Therefore, when the shutter member is moved to expose the recording and/or reproduction aperture, it swings around the base so that the front end of the shutter member may remarkably lift up from the surface of the cartridge main body.
Such a lifting up phenomenon of the shutter member can be suppressed by reducing the length of the shutter section thereof. However, if the length of the shutter section is reduced, the length of the recording and/or reproduction aperture has also to be reduced. Then, the signal recording region of the disc-shaped recording medium that is contained in the cartridge main body cannot be exposed largely between the inner and outer peripheries thereof In other words, the area of the signal recording region of the disc-shaped recording medium needs to be reduced to make it difficult to provide the disc-shaped recording medium with a large recording capacity.
Meanwhile, efforts have been and are being paid to realize a high density recording on disc-shaped recording mediums and it is current possible to record a considerably large volume of information on a small disc-shaped recording medium. Then, disc cartridges for containing such a small disc-shaped recording medium are also downsized.
As the small disc-shaped recording medium contained in a downsized disc cartridge is made to be exposed largely between the inner and outer peripheries thereof in order to increase the area of the signal recording region, the recording and/or reproduction aperture is forced to extend its length between the inner and outer peripheries of the disc-shaped recording medium. However, the width of the area where the shutter member moves cannot be increased in proportion to the increased length. In other words, the width of the recording and/or reproduction aperture has to be inevitably limited if the shutter member is to be moved within the area of the cartridge main body in order to reliably expose the recording and/or reproduction aperture. As a result, the shutter section of the shutter member for closing the recording and/or reproduction aperture is made to show an oblong profile. As the shutter member having such an oblong shutter section is driven to move by the force applied to the base of the shutter section, it swings around the base and its front end remarkably moves up from the corresponding surface of the cartridge main body.
If the shutter member moves up from the cartridge main body when the disc cartridge is loaded in the recording and/or reproduction apparatus, it is no longer possible to reliably load and unload the disc cartridge and the disc cartridge and the mechanical part of the recording and/or reproduction apparatus can be damaged.
Additionally, in the downsized disc cartridge, if the recording and/or reproduction aperture is formed to largely expose the disc-shaped recording medium between the inner and outer peripheries thereof, the open area of the disc cartridge including the drive aperture is increased to reduce the physical strength of the cartridge main body.
Japanese Patent Application Laid-Open Publication No. 2001-314 discloses a disc cartridge having a cartridge main body that is provided with recording/reproduction apertures on the opposite surfaces thereof and shutter members for opening and closing the respective apertures and adapted to prevent the front end of the shutter section for opening and closing a region extending from the recording and/or reproduction aperture to the drive aperture of one of the surfaces from lifting up.